Source of light for photography



A iil 27, 1937. w scHNElDER 2,078,689.

SOURCE OF LIGHT FOR PHOTOGRAPHY Filed Dec. 3 1935 In ven for WJZ/zedm Schneider Q By his Attorneys Patented Apr. 27, 1937 UNITED STATES SOURCE OF LIGHT FOR PHOTOGRAPHY Wilhelm Schneider, Dessau in Anhalt, Germany,

assignor to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-the-Main, Germany Application December 3, 1935, Serial No. 52,628 In Germany December 5, 1934 2 Claims.

My present invention relates to a source of light for photographic and projection purpose. One of its objects is a process of stabilizing the arc of an arc lamp. Another object is to prevent o glowing particles which split from the carbons of an arc lamp from being deposited on the transparent vessel which surrounds the arc. Still another object is an improved source of light for photographic and projection purposes. Further objects will be seen from the detailed specification following hereafter. Reference is made to the accompanying drawing in which Fig. 1 shows a front view of a source of light in accordance with the invention,

Fig. 2 is a sectional detail of the lower carbon holder, and

Fig. 3 shows a perspective view of a modified source of light in accordance with the invention. It is known that by confining carbon electrodes of an arc lamp in an indifferent gas, for example carbon monoxide or nitrogen, the combustion of the carbon is minimized and, particularly in the case of nitrogen, the light has a higher actinic value for photographic layers sensitive to blue. In practice this system is open to the objection that the glass globes or the like required are of considerable size. It has not been possible to reduce the dimensions of the globe below a certain value because of the danger of cracking them and because particles scattered fromthe electrodes and the inorganic constituents of the carbons form a firm coating on the walls of the globe, the translucency of which they reduce. Moreover, the arc does not usually burn steadily, but shifts around the electrodes and flickers.

This invention improves the unfavorable conditions referred to above by confining the arc in an indifferent gas in a narrow closed cylinder of transparent material, for instance glass or quartz, or of an opaque material having transparent windows, in which cylinder the gas is caused by suitable mechanical means to circulate around the arc. The scattered particles and other products of combustion are thus prevented from arriving at and hence deposited on the wall of the cylinder; instead they are carried upwards i rapidly by the current of gas and may be ejected through apertures arranged radially in. the wall. Furthermore, the arc is accurately centered by the rotating column of gas and is quite stable and free from shifting or flickering.

The last mentioned advantage which is most essential may also be obtained by producing the arc of the arc lamp in a closed vessel filled with nitrogen and circulating the nitrogen by a fan.

The invention will now be described with reference to the accompanying drawing.

Referring to Figures 1 and 2, I is a vessel of transparent material (glass or quartz) mounted between plates 2 and 3 connected by rods Ill. The plate 2 carries a bearing 5 for a hollow rotatable shaft 4 carrying a carbon electrode 6 and a fan II. The other carbon electrode 1 extends through the plate 3. The shaft 4 is rapidly rotated by suitably driving a pulley 9 secured to it, current being supplied to the electrode 6 through the shaft 4 by way of the spring contacts 8. Owing to this rapid rotation, the gas in the vessel l is caused by the fan II to follow a helical course around the electrodes. 82 designates a knob for actuating a lubricating device (not shown) for the bearing 5.

Referring to Fig. 3, I2 is a cylindrical vessel, for instance, of metal. This vessel I2 is provided with a transparent window I4, for instance of quartz. Behind the window I4 is seen the arc l3 which is produced between the carbons 6 and I introduced through the two ends of the cylindrical vessel l2. The upper end of the vessel I2 is provided with openings l5 through which the nitrogen can escape which is blown in radial direction into the vessel l4 through the pipes Hi.

What I claim is:

1. An arc lamp for photographic and projection purposes which comprises a transparent vessel open at its two ends, two plates for closing said two ends of said vessel, means for pressing said plates against said vessel, a carbon introduced through one of said plates, a hollow axle introduced through the other plate, a carbon mounted in said hollow axle said carbon being in alignment with said first named carbon, a bearing mounted on said second named plate for rotatably locating said hollow axle, rubbing spring contacts mounted to said rods and sliding on said hollow axle for supplying electric current to said carbon mounted in said hollow axle, a wheel mounted on the end of said hollow axle opposite to that which carries the carbon, for driving said axle, and a fan mounted on said hollow axle inside said transparent vessel.

2. An arc lamp comprising a transparent openended vessel, a closure plate on each end thereof, means for holding said plates in place, a carbon carried by one plate, a. hollow axle rotatably mounted on said other plate, a carbon mounted on said hollow axle in alignment with said first carbon, a fan rigidly mounted on said axle within said vessel, means for rotating said axle and means for supplying current to the carbon in said axle.

WILI-IELM SCHNEIDER. 

